Method of detecting metal particles in sheet material



Feb. 14, 1933. MANEGOLD 1,897,731

METHOD OF DETECTING METAL PARTICLES IN SHEET MATERIAL Filed Feb. 1'7,1928 Patented Feb. 14, 1 933 ROBERT A. MANEGOLD, OF MILWAUKEE, WISCONSINMETHOD OF DETECTING METAL PARTICLES IN SHEET MATERIAL Application filedFebruary 17, 1928.

The present invention relates in general to an improved process ofdetecting and thereby facilitating removal of pieces of metal fromsheets of material in which the pieces may have been embedded, andrelates more specifically to an improved method of locatingobjectionable metallic particles while they are concealed in permanentsheets of a substancesuch as paper, felt or the like, in order to enablesubsequent removal of the detected particles.

A general object of the invention is to provide an improved method ofdetecting and of facilitating removal of metallic particles frompermanent sheets of material in which the particles may be eitherpartially or completely embedded, by taking advantage of differences inthe characteristics of the substances to determine the location of J3the particles.

t is common practice in the commercial production of hair felt and thelike, to interweave or intertwine the hair with a fabric binder by meansof mechanically reciprocated steel needles which push and pull the hairthrough the meshes thus produce the sheet. During the felt manufacturingprocess, the needles frequently break and relatively small pieces orparticles of the metal, such as the point portions of the needles,become embedded or concealed in the felt sheets. The hidden metalparticles are snugly confined within the felt by the hair wrapped aboutthem, and are a source of considerable annoyance and extreme dangerduring the subsequent severance of the felt into smaller sheets, pads,wads, etc, and when handling or utilizing articles manufactured from thefelt. It is therefore exceedingly desirable to remove the metal piecesor particles from the felt, immediately after the sheets have beenproduced. lVhile a number of methods of detecting the location of suchobjectionable metal particles in sheet material, such as the use ofX-ray machines, have heretofore been proposed, none of these priormethods have proven commercially satisfactory.

It is a more specific object of the present invention to provide asimple and reliable of the fabric and Serial No. 255,203.

process of quickly and positively detecting pieces of magnetic materialsuch as steel, concealed within sheets of fibrous substance such as hairfelt, in order to facilitate subsequent removal of the metal. Theimproved process is capable of being carried 011 continuously with theaid of relatively standard equipment, and insures detection of allmetallic particles having magnetic qualities, which may be associatedWith the sheets treated in accordance with the improvement.

A clear conception of the various steps of the improved process, and ofthe construction and operation of several assemblages of apparatus forexploiting the same, may be had from the accompanying drawing and thefollowing detailed description. While four distinct embodiments of theinvention have been specifically described and shown in Figs. 1 to 6inclusive of the drawing by way of illustration, it will be understoodthat other practical embodiments within the contemplation of the presentimprovement, may occur to individuals skilled in the art.

In accordance with one specific embodiment of the invention illustrateddiagrammatically in Figs. 1 and 2 of the drawing, the sheets of fibrousmaterial 7 such as hair felt, are advanced either constantly orintermittently but at a relatively slow rate of speed, in closeproximity to an electro-magnet 8 or a powerful permanent magnet. Thistransportation may be effected with an ordinary belt conveyor 9 and anymetallic particles 10 such as steel needle points which may be embeddedin the felt are magnetized while passing through the field of the magnet8, in a well known manner. The sheet of material 7 after passing throughthe energizing magnetic field, may be subsequently transported in closeproximity to a series of compasses or similar detectors 11 which arepreferably disposed beyond the range of action of the energizing field,and the magnetic needles of which normally point across or laterally ofthe path of travel of the sheets. When the concealed and magnetizedmetallic particles 10 pass near the magnetic needles, the particlesimmediately function to deflect the adjacent needles away from theirnormal north-south position, and cause the compass needles to pointtoward the advancing particles. An attendant upon observing thedirection of deflection of the compass needles may readily locate andsubsequently remove the hidden metallic particles from the sheet. Inorder to insure detection of all of the embedded metal pieces, allportions of the felt should be advanced through the energizing magneticfield, and a suflicient number of compass needles must be employed sothat hidden particles in all portions of the sheets will influence atleast one or more of the magnetic detector needles. The energizingmagnets 8 may be disposed directly beneath the felt conveying belt, andthe compass needles may be located in staggered rows directly above thesheets some distance beyond the magnets. It will be apparent from theforegoing description, that the energizing magnets and the detectorneedles provide simple and reliable means for quickly and positivelydetecting or locating the successively advancing metallic particles 10concealed within the felt, thereby facilitating subsequent removalthereof if such removal is desired.

In accordance with another specific embodiment of the inventionillustrated diagrammatically in Fig. 3 of the drawing, the sheets offibrous material 7 may be placed or d posited. upon the upper end of aninclined surface 12 having an angle slightly less than the angle ofrepose. The supporting surface 12 may then be vibrated by means of avibrator 13 so as to cause the fibrous sheet to slowly gravitate towardthe lower end of the incline. One or more rela tively powerful magnets 8located adjacent to the incline and having magnetic fields through whichall portions of the advancing sheets must pass, will interrupt thedownward travel of the sheets when an embedded particle of metal entersthe range of action of the magnets. The sheets will thus be held againstfurther movement until the hidden metal particle has been removed or thesheet otherwise released. In this man ner the presence of metalparticles and the location thereof may be readily determined with theaid of a single magnetic device.

In accordance with still another specific embodiment of the inventionillustrated diagrammatically in Fig. d of the drawing, the sheets offibrous material 7 may be slowly advanced in a normally straight path,along a definite course. One or more relatively powerful magnets 14having wave shape pole pieces may be positioned adjacent to the path oftravel of the sheets, in

such manner that the tractive effort of the magnets acting upon hiddenmetal particles embedded in the advancing sheets, w1ll cause the sheetsto be momentarily withdrawn from their normal path of travel therebygiving a visible indication of the existence of a hidden metal particlein the offset portion of the sheet. An attendant observing the offsetmotion of the sheet may then readilylocate the metal particle orparticles, and may removethe same if desired. In this manner, thepresence of metallic particles and the location thereof, may likewise bedetermined with the aid of a single magnetic device.

In accordance with still a further embodiment of the inventionillustrated diagrammatically in Figs. 5 and 6 of the drawing, the sheetsof fibrous material 7 may be slowly advanced by gravity or otherwise,along an inclined plane 15 in a normally straight downward direction.One or more relatively powerful magnets 16 having pole pieces set on thebias relative to the direction of normal travel of the sheets, may bepositioned adjacent to the path of advancement so that the tractiveeffort of the magnets acting upon hidden metal particles embedded withinthe moving sheets, will cause said sheets to be deflected from theirnormal straight path of travel and to move diagonally or at an anglethereto. An attendant upon observing the diagonal movement of the sheet,may then conveniently locate the metal particle and may if desired,remove the same. This apparatus may also be utilized to segregate thesheets containing metal particles from those which are free from metal,the diagonal motion being utilized to deposit the sheets with metaltherein in receptacles located laterally of the receptacles whichreceive the other sheets. In this manner, the presence of metalparticles may also be determined with the aid of a single magneticdevice.

From the foregoing description of several forms of apparatus forexploiting the improved process, it will be apparent that the presentinvention provides a simple and extremely effective method of detectingthe presence of metallic substances 10 in permanent sheets ofnon-metallic or non-magnetic material 7. The removal of the detectedparticles may not be necessary in all cases, as it may be possible toutilize sheet material containing embedded metal particles for certainpurposes, and the present detecting method will then be employed only tosegregate the sheets containing metal particles 10 from those which arefree from such particles. In all cases, the presence of metallicparticles is elfectively deter mined by virtue of the magneticcharacteristics of these particles, and the non-magnetic characteristicsof the sheets, with the aid of one or more magnets. While the use ofcompass or other types of detector needles actin u on the reviousl manetized particles, will perhaps provide a more positive and sensitivemeans of detecting the presence of metal particles, the mere use ofmagnets without auxiliary detectors will probably suffice in cases wherethe existence of minute metal particles within the sheets is notseriously objectionable.

lVhile the invention has been specifically described as being especiallyapplicable for the purpose of detecting the presence of steel needlepoints or the like in hair felt, it will be apparent that the process iscapable of more general application. The improvement is especiallyapplicable in the treatment of permanent sheets wherein the embeddingand confinement of the metal particles is such that the particles cannotbe withdrawn from the sheets by the tractive effort of a magnet alone.It will be apparent that the principles involved are readily applicableto the treatment of other than hair felts and to the treatment ofcertain kinds of paper and composition board, as well as to thetreatment of fabric and rubher sheets.

It should be understood that it is not desired to limit the invention tothe exact sequence of the process steps or to the details ofconstruction of the apparatus specifically described herein, for variousmodifications within the scope of the claims may occur to presonsskilled in the art.

It is claimed and desired to secure by Letters Patent l. The method ofridding sheets of nonmagnetic material of embedded metal particles,which comprises, subjecting all portions of each sheet of the materialto the direct influence of a powerful magnetic field to permanentlymagnetize embedded magnetizable metal particles, utilizing themagnetization of said particles to definitely determine the locationthereof both laterally and longitudinally of the sheet, and subsequently removing the detected particles.

2. The method of ridding sheets of nonmagnetic felt of embedded metalparticles, which comprises, advancing all portions of each sheet througha powerful magnetic field to permanently magnetize the embeddedmagnetizable metal particles, subsequently advancing the sheet inproximity to a compass needle to cause the needle to definitely locatethe magnetized particles both laterally and longitudinally of the sheet,and finally removing the detected particles.

In testimony whereof, the signature of the inevntor is afiixed hereto.

ROBERT A. MANEGOLD.

